* Dor Laor <[email protected]> wrote:
> Hi Ingo, Thomas,
>
> In the latest kernel (2.6.24-rc3) I noticed a drastic performance
> decrease for KVM networking. The reason is many vmexit (exit reason is
> cpuid instruction) caused by calls to gettimeofday that uses tsc
> sourceclock. read_tsc calls get_cycles_sync which might call cpuid in
> order to serialize the cpu.
>
> Can you explain why the cpu needs to be serialized for every gettime
> call? Do we need to be that accurate? (It will also slightly improve
> physical hosts). I believe you have a reason and the answer is yes. In
> that case can you replace the serializing instruction with an
> instruction that does not trigger vmexit? Maybe use 'ltr' for example?
hm, where exactly does it call CPUID?
Ingo
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
